Cathode for a battery

ABSTRACT

An electrode for an electrochemical cell including an active electrode material and an intrinsically conductive coating wherein the coating is applied to the active electrode material by heating the mixture for a time and at a temperature that limits degradation of the cathode active material.

This application is a continuation of co-pending U.S. application Ser.No. 13/831,924 filed Mar. 15, 2013 entitled “Cathode for a Battery,”which is a continuation-in-part of co-pending U.S. application Ser. No.13/612,800 filed Sep. 12, 2012 entitled “Cathode for a Battery,” whichin turn claims priority to and the benefit of U.S. ProvisionalApplication No. 61/533,911 filed Sep. 13, 2011 entitled “Cathode forMetal-Fluoride Battery” and U.S. Provisional Application No. 61/621,205filed Apr. 6, 2012 entitled “Cathode for a Battery,” each of which isincorporated herein by reference in its entirety. This applicationclaims priority to and the benefit of each of the above applications.

BACKGROUND OF THE INVENTION

The present invention is in the field of battery technology and, moreparticularly, in the area of using coatings to enhance electrolyte andelectrode performance in batteries including metal-fluoride,carbon-fluoride, or oxide-based electrode materials.

One type of battery consists of a negative electrode made primarily fromlithium and a positive electrode made primarily from a compoundcontaining carbon and fluorine. During discharge, lithium ions andelectrons are generated from oxidation of the negative electrode whilefluoride ions and carbon are produced from reduction of the positiveelectrode. The generated fluoride ions react with lithium ions near thepositive electrode to produce a compound containing lithium andfluorine, which may deposit at the positive electrode surface.

Lithium/carbon-fluoride batteries enjoy widespread use and commercialapplicability in part due to certain desirable characteristics. Thecarbon-fluoride positive electrode is lightweight, which makes thebattery desirable in portable or mobile applications where weight is animportant design consideration. Also, the carbon-fluoride positiveelectrode has a high capacity. Further, the overall reaction has a highelectrochemical potential.

Another type of battery consists of a negative electrode made primarilyfrom lithium and a positive electrode made primarily from a compoundcontaining metal oxides. During charge and discharge cycles, lithiumions migrate from one electrode to the other where the direction ofmigration depends on the cycle.

Despite their widespread use, both types of batteries suffer fromcertain challenges.

The batteries have comparatively low electrical and ionic conductivityas compared to certain other battery materials. Such comparatively lowelectrical and ionic conductivity can have the following results in anelectrochemical cell: comparatively low power; comparatively lowoperating voltage; comparatively large underpotential upon discharge;and a comparatively low capacity during a high rate of discharge.

The batteries have comparatively low thermal conductivity as compared tocertain other battery materials and such comparatively low thermalconductivity can result in comparatively significant heat generation bythe electrochemical cell upon discharge.

There have been prior attempts to address such challenges. One priorattempt involves forming a composite positive electrode. The rawcomposite material contains a carbon-fluoride compound and a secondcompound, which is comparatively more electrically conductive than thecarbon-fluoride compound. These two compounds are mixed together to forma composite material that is then formed into a positive electrode.

One example of such a composite material is a carbon-fluoride compoundcomposited with silver vanadium oxide (silver vanadium oxide is oftenabbreviated as “SVO” in the battery industry rather than by its periodictable symbols). This CF/SVO composite material has been used to form apositive electrode in a battery for use in medical devices and hasdemonstrated increased pulse power and increased energy density whencompared to a battery using a positive electrode formed only fromcarbon-fluoride.

Another example of a composite material for use in forming a positiveelectrode is a carbon-fluoride compound composited with manganesedioxide (MnO₂). This CF/MnO₂ composite material has been used to form apositive electrode where cost is a key design factor and hasdemonstrated increased power at high discharge rates, increased energydensity, and reduced heat buildup in the electrochemical cell whencompared to a battery using a positive electrode formed only fromcarbon-fluoride.

Although prior batteries using positive electrodes formed from these andcertain other composite materials generally have higher power, higheroperating potential, lower underpotential, and less heat buildup whencompared to batteries using a positive electrode formed only frommetal-fluoride or carbon-fluoride, the performance of theelectrochemical cell could be improved significantly. Also, certain ofthese performance improvements come at the expense of reduced energydensity.

In some prior batteries, conductive coatings have been applied toelectrode materials. In secondary battery applications, some electrodeshave been formed from carbon-coated LiFePO₄. Also, some research hasoccurred on coating carbon-fluoride compounds used for electrodes inprimary batteries (see Q. Zhang, et al., Journal of Power Sources 195(2010) 2914-2917). Prior art coatings are typically applied at hightemperatures and under inert atmosphere which can degrade cathode activematerials. Thus, temperature-sensitive active materials for cathodeshave not typically been coated with conductive carbon materials.

Certain embodiments of the present invention address the challengesfound in batteries. Certain embodiments of the present invention can beused to form electrochemical cells for batteries that exhibit lowerunderpotential, higher power, higher capacity at a high discharge rate,less heat generation, or faster heat dissipation when compared to priorbatteries.

These and other challenges can be addressed by embodiments of thepresent invention described below.

BRIEF SUMMARY OF THE INVENTION

Certain embodiments of the invention include an electrode for anelectrochemical cell including an active electrode material, a bindermaterial, and an intrinsically conductive coating wherein the coating isapplied to the active electrode material. In certain embodiments, theintrinsically conductive coating is formed from an organic coatingcompound comprising a conjugated core. In certain embodiments, theintrinsically conductive coating is formed from an organic coatingcompound comprising a conjugated core in which at least 90% of thecarbon atoms are sp or sp2 hybridized. In certain embodiments, theintrinsically conductive coating is formed from an organic coatingcompound in which at least 35% of the carbon atoms are sp or sp2hybridized.

Certain embodiments of the invention include a method of making anelectrode for an electrochemical cell including combining a coatingcompound characterized by having an intrinsic conductivity and an activeelectrode material to form a mixture, heating the mixture to form aconductively coated active electrode material, wherein the mixture isheated for a time and at a temperature that limits degradation of theactive electrode material, mixing the conductively coated activeelectrode material with a binder material and a conductive additive toform an electrode-forming mixture, and heating the electrode-formingmixture to form the electrode. In certain embodiments, the coatingcompound is heated at less than about 450 degrees C. In certainembodiments, the coating compound is heated for a time in a range offrom about 0 hours to about 6 hours.

Certain embodiments include the method of making an electrochemical cellcontaining coated cathode materials and methods of use of suchelectrochemical cells.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A and 1B depict the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved voltage performance.

FIG. 2 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved pulse power performance.

FIG. 3 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved pulse power performance.

FIG. 4 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved pulse power performance.

FIG. 5 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved pulse power performance versus depth ofdischarge.

FIG. 6 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved pulse power performance versus depth ofdischarge.

FIG. 7 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved voltage performance as a function ofcapacity.

FIGS. 8A and 8B depict the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved voltage performance as a function ofcapacity.

FIG. 9 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved voltage performance as a function ofcapacity.

FIGS. 10A and 10B depict the results of testing of an electrochemicalcell containing cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved capacity retention.

FIG. 11 depicts the results of testing of an electrochemical cellcontaining cathode active materials coated according to certainembodiments of the invention as compared to control. Certain coatingmaterials demonstrate improved voltage performance.

FIG. 12 depicts the results of testing of an electrochemical cellcontaining metal fluoride active materials coated according to certainembodiments of the invention as compared to control. Certain coatedmetal fluoride materials demonstrate improved rate capability ascompared to control while other coated metal fluoride materialsdemonstrate diminished rate capability as compared to control.

FIG. 13 depicts the results of testing of an electrochemical cellcontaining metal fluoride active materials coated according to certainembodiments of the invention as compared to control. A CuF₂/MoO₃composite material coated with anthracene demonstrated improved rateperformance as compared to an uncoated CuF₂/MoO₃ composite material.

FIG. 14 depicts the results of testing of an electrochemical cellcontaining metal fluoride active materials coated according to certainembodiments of the invention. A metal fluoride material coated withanthracene demonstrated a minimal voltage drop from low rate to highrate of discharge.

FIG. 15 depicts the results of testing of an electrochemical cellcontaining metal fluoride active materials coated according to certainembodiments of the invention, demonstrating a low voltage drop from lowrate to high rate of discharge and improved energy density.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions apply to some of the aspects described withrespect to some embodiments of the invention. These definitions maylikewise be expanded upon herein. Each term is further explained andexemplified throughout the description, figures, and examples. Anyinterpretation of the terms in this description should take into accountthe full description, figures, and examples presented herein.

The singular terms “a,” “an,” and “the” include the plural unless thecontext clearly dictates otherwise. Thus, for example, reference to anobject can include multiple objects unless the context clearly dictatesotherwise.

The terms “substantially” and “substantial” refer to a considerabledegree or extent. When used in conjunction with an event orcircumstance, the terms can refer to instances in which the event orcircumstance occurs precisely as well as instances in which the event orcircumstance occurs to a close approximation, such as accounting fortypical tolerance levels or variability of the embodiments describedherein.

The term “about” refers to the range of values approximately near thegiven value in order to account for typical tolerance levels,measurement precision, or other variability of the embodiments describedherein.

The terms “coating,” “coat,” “coated,” and the like refer to arelatively thin film of material on the surface of a substrate and theprocess of making the same. The terms include films that are continuousand films that are discontinuous.

The terms “conductive,” “conductor,” “conductivity,” and the like referto the intrinsic ability of a material to facilitate electron or iontransport and the process of doing the same. The terms include materialswhose ability to conduct electricity may be less than typically suitablefor conventional electronics applications but still greater than anelectrically-insulating material.

The term “core” and the like refers to the central moiety of a moleculeas opposed to pendant groups on the molecule. The core may occupy theentire molecule. The shape of the molecule is not determinative of thepresence or lack of a core.

The term “solvent” and the like refers to a materials capable of atleast partially dissolving another material. The term includes a singlesolvent or a mixture containing one or more solvents, and such mixturecan include non-solvents.

The term “slurry” and the like refers to a mixture in which at leastsome amount of one or more components is not dissolved in the solvent,and includes mixtures of two materials where the mixture is formedwithout a solvent or the mixture that results when the solvent issubstantially removed but before the final product or article to be madefrom the mixture has been formed.

The term “active material” and the like refers to the material in anelectrode, particularly in a cathode, that donates, liberates, orotherwise supplies the conductive species during an electrochemicalreaction in an electrochemical cell.

Certain embodiments of the invention relate to compounds useful for theformation of conductive coatings on active materials. Preferably, thecompounds of embodiments of the invention are used to coat activematerials that degrade, decompose, or are otherwise rendered unsuitableor undesirable for use after exposure to high temperatures or hightemperature under an inert atmosphere, where high temperatures are thosehigher than about 500 degrees C. The compounds are capable of formingconductive coatings at temperatures less than about 500 degrees C. onsuch active materials.

In certain embodiments, conductive coatings are used to improve theelectrical conductivity of desirable active materials, includingmetal-fluoride and carbon-fluoride active materials. In certainembodiments, conductive coatings are used to improve the electricalconductivity of iron-fluoride compounds (such as FeF₃),manganese-fluoride compounds (such as MnF₃), copper-fluoride compounds(such as CuF₂), and carbon-fluoride compounds. In certain embodiments,conductive coatings are used to improve the electrical conductivity oflithium-manganese-nickel-oxygen (LMNO) compounds,lithium-manganese-oxygen (LMO) compounds, and lithium-rich layered oxidecompounds. More generally, conductive coatings are used to improveactive materials for cathodes including phosphates, fluorophosphates,fluorosulphates, silicates, spinels, and composite layered oxides.

For example, a class of suitable phosphate active materials can berepresented as: Li_(a)(M1_(b)M2_(c)M3_(d)M4_(e))_(f)PO₄, where M1, M2,M3, and M4 can be the same or different, M1 is Mn, Co, or Ni, M2 is atransition metal, such as Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, or Mo, M3is a transition metal or a main group element, optionally excludingelements of Group VIA and Group VIIA, M4 is a transition metal or a maingroup element, optionally excluding elements of Group VIA and GroupVIIA, 1.2≧a≧0.9 (or 1.2>a>0.9), 1≧b≧0.6 (or 1>b>0.6), 0.4≧c≧0 (or0.4>c>0), 0.2≧d≧0 (or 0.2>d>0), 0.2≧e≧0 (or 0.2>e>0), and 1.2≧f≧0.9 (or1.2>f>0.9). Additional details regarding this class of active materialscan be found in Goodenough et al., “Challenges for Rechargeable LiBatteries,” Chemistry of Materials 22, 587-603 (2010); Marom et al., “Areview of advanced and practical lithium battery materials,” J. Mater.Chem., 21, 9938 (2011); Zhi-Ping et al., “Li-Site and Metal-Site IonDoping in Phosphate-Olivine LiCoPO₄ by First-Principles Calculation,”Chin. Phys. Lett. 26 (3) 038202 (2009); and Fisher et al., “LithiumBattery Materials LiMPO₄ (M) Mn, Fe, Co, and Ni): Insights into DefectAssociation, Transport Mechanisms, and Doping Behavior,” Chem. Mater.2008, 20, 5907-5915; the disclosures of which are incorporated herein byreference in their entirety.

For example, another class of suitable phosphate active materials cancomprise lithium (Li), cobalt (Co), a first transition metal (M1), asecond transition metal (M2) different from M1, and phosphate (PO₄),where M1 and M2 are each selected from iron (Fe), titanium (Ti),vanadium (V), niobium (Nb), zirconium (Zr), hafnium (Hf), molybdenum(Mo), tantalum (Ta), tungsten (W), manganese (Mn), copper (Cu), chromium(Cr), nickel (Ni), and zinc (Zn) (e.g., as dopants and/or oxidesthereof), and can have molar ratios of Li:Co:M1:M2:PO₄ defined by(1-x):(1-y-z):y:z:(1-a), respectively, optionally represented (as ashorthand notation) as:Li_((1-x)):Co_((1-y-z)):M1_(y):M2_(z):(PO₄)_((1-a)), where −0.3≦x≦0.3;0.01≦y≦0.5; 0.01≦z≦0.3; −0.5≦a≦0.5; and 0.2≦1-y-z≦0.98. Preferably, M1and M2 are each selected from iron (Fe), titanium (Ti), vanadium (V) andniobium (Nb) (e.g., as dopants and/or oxides thereof). Preferably, M1 isiron (Fe) (e.g., as a dopant and/or oxide thereof), M2 is selected fromtitanium (Ti), vanadium (V), and niobium (Nb) (e.g., as dopants and/oroxides thereof). Preferably, −0.3≦x<0, −0.2≦x<0, or −0.1≦x<0.Preferably, M2 is Ti, and 0.05≦z≦0.25 or 0.05≦z≦0.2. Preferably, M2 isV, and 0.03≦z≦0.25 or 0.05≦z≦0.2. Preferably, 0.3≦1-y-z≦0.98,0.5≦1-y-z≦0.98, or 0.7≦1-y-z≦0.98. Additional details regarding thisclass of cathode materials can be found in co-pending and co-owned U.S.Provisional Application No. 61/426,733, entitled “Lithium Ion BatteryMaterials with Improved Properties” and filed on Dec. 23, 2010, thedisclosure of which is incorporated herein by reference in its entirety.

For example, a class of suitable fluorophosphates active materials canbe represented as: Li_(a)(M1_(b)M2_(c)M3_(d)M4_(e))_(f)PO₄F_(g), whereM1, M2, M3, and M4 can be the same or different, M1 is Mn, Co, or Ni, M2is a transition metal, such as Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, or Mo,M3 is a transition metal or a main group element, optionally excludingelements of Group VIA and Group VIIA, M4 is a transition metal or a maingroup element, optionally excluding elements of Group VIA and GroupVIIA, 1.2≧a≧0.9 (or 1.2>a>0.9), 1≧b≧0.6 (or 1>b>0.6), 0.4≧c≧0 (or0.4>c>0), 0.2≧d≧0 (or 0.2>d>0), 0.2≧e≧0 (or 0.2>e>0), 1.2≧f≧0.9 (or1.2>f>0.9), and 1.2≦g≦0 (or 1.2>g>0).

For example, a class of suitable fluorosilicate active materials can berepresented as: Li_(a)(M1_(b)M2_(c)M3_(d)M4_(e))_(f)SiO₄, where M1, M2,M3, and M4 can be the same or different, M1 is Mn, Co, or Ni, M2 is atransition metal, such as Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, or Mo, M3is a transition metal or a main group element, optionally excludingelements of Group VIA and Group VIIA, M4 is a transition metal or a maingroup element, optionally excluding elements of Group VIA and GroupVIIA, 2.2≧a≧0.9 (or 2.2>a>0.9), 1≧b≧0.6 (or 1>b>0.6), 0.4≧c≧0 (or0.4>c>0), 0.2≧d≧0 (or 0.2>d>0), 0.2≧e≧0 (or 0.2>e>0), and 1.2≧f≧0.9 (or1.2>f>0.9).

For example, a class of suitable spinel active materials can berepresented as: Li_(a)(M1_(b)M2_(c)M3_(d)M4_(e))_(f)O₄, where M1, M2,M3, and M4 can be the same or different, M1 is Mn or Fe, M2 is Mn, Ni,Fe, Co, or Cu, M3 is a transition metal, such as Ti, V, Cr, Mn, Fe, Co,Ni, Zr, Nb, or Mo, and M4 is a transition metal or a main group element,optionally excluding elements of Group VIA and Group VIIA, 1.2≧a≧0.9 (or1.2>a>0.9), 1.7≧b≧1.2 (or 1.7>b>1.2), 0.8≧c≧0.3 (or 0.8>c>0.3), 0.1≧d≧0(or 0.1>d>0), 0.1≧e≧0 (or 0.1>e>0), and 2.2≧f≧1.5 (or 2.2>f>1.5).LMNO-type cathode materials, such as Li_(1.05)Mn_(1.5)Ni_(0.5)O₄, andLMO-type materials, such as LiMn₂O₄, are included in this class.Additional details regarding this class of cathode materials can befound in Goodenough et al., “Challenges for Rechargeable Li Batteries,”Chemistry of Materials 22, 587-603 (2010); Marom et al., “A review ofadvanced and practical lithium battery materials,” J. Mater. Chem., 21,9938 (2011); and Yi et al., “Recent developments in the doping ofLiNi_(0.5)Mn_(1.5)O₄ cathode material for 5 V lithium-ion batteries,”Ionics (2011) 17:383-389; the disclosures of which are incorporatedherein by reference in their entirety.

For example, a class of suitable Li-rich layered oxide active materialscan be represented as: Li(Li_(a)M1_(b)M2_(c)M3_(d)M4_(e))_(f)O₂, whereM1, M2, M3, and M4 can be the same or different, M1 is a transitionmetal, such as Mn, Fe, V, Co, or Ni, M2 is a transition metal, such asMn, Fe, V, Co, or Ni, M3 is a transition metal, such as Mn, Fe, V, Co,or Ni, M4 is a transition metal or a main group element, optionallyexcluding elements of Group VIA and Group VIIA, 0.4≧a≧0.05 (or0.4>a>0.05), 0.7≧b≧0.1 (or 0.7>b>0.1), 0.7≧c≧0.0 (or 0.7>c>0.0),0.7≧d≧0.0 (or 0.7>d>0.0), 0.2≧e≧0 (or 0.2>e>0), and 1.2≧f≧0.9 (or1.2>f>0.9). OLO-type materials are included in this class. Additionaldetails regarding this class of cathode materials can be found inGoodenough et al., “Challenges for Rechargeable Li Batteries,” Chemistryof Materials 22, 587-603 (2010); Marom et al., “A review of advanced andpractical lithium battery materials” J. Mater. Chem., 21, 9938 (2011);Johnson et al., “Synthesis, Characterization and Electrochemistry ofLithium Battery Electrodes: xLi₂MnO₃(1-x)LiMn_(0.333)Ni_(0.333)Co_(0.333)O₂ (0<x<0.7),” Chem. Mater., 20,6095-6106 (2008); and Kang et al., “Interpreting the structural andelectrochemical complexity of 0.5Li₂MnO₃.0.5LiMO₂ electrodes for lithiumbatteries (M=Mn_(0.5-x)Ni_(0.5-x)Co_(2x), 0=x=0.5),” J. Mater. Chem.,17, 2069-2077 (2007); the disclosures of which are incorporated hereinby reference in their entirety.

According to certain embodiments, active materials are coated using aprecursor material. Suitable precursor materials facilitate thedeposition of a conductive coating onto the active material, and inparticular onto particles of the active material.

In certain embodiments, the precursor is a carbon-containing material.In these embodiments, the carbon precursor can be a polymer or apolymeric material. More generally, the carbon precursor can be anythingthat decomposes to form a conductive carbon upon heating (e.g.,polymers, sugars, various biomolecules, etc.). Preferably, the precursordecomposes (or, in the specific case of carbon precursors, “carbonizes”)below the decomposition temperature of the active material. For example,carbon-fluoride active materials may show substantial decomposition whenheated to a temperature in the range from about 550 degrees C. to about700 degrees C. Other examples of suitable carbon precursors includesucrose, poly(ethylene glycol), poly(vinylidene fluoride), polyacetal,polystyrene, polybutadiene, poly(vinyl alcohol), poly(vinyl chloride),polytetrafluoroethylene, polypropylene, polyethylene, poly(methylmethacrylate), polycarbonate, cellulose, carboxymethyl cellulose, andcombinations thereof. Preferably, the polymer precursor producessubstantially graphitic carbon coatings at temperatures below the rangeof decomposition temperatures for the carbon-fluoride active materials.

According to certain embodiments, the compounds useful for the formationof conductive carbon coatings on active materials are organic moleculeswith delocalized electron configurations. According to certainembodiments, the compounds are conductive organic molecules. It isunderstood that any compound with a high degree of electrondelocalization or any compound with high conductivity could be used toform conductive coatings on active materials.

Generally speaking, delocalized electrons are electrons that are notlimited to the orbital of a single atom, in the case of ions or metals,or a single covalent bond, in the case of organic materials. Incarbon-based materials, bonds including a carbon atom can be a sourcefor delocalized electrons when more than one of the four electrons inthe outer energy levels of the carbon atom is in a covalent bond withanother atom. Often, electron delocalization occurs in carbon-carbonbonds. These bonds are sometimes referred to as conjugated bonds.

According to hybridization theory, delocalized electrons can bedescribed as mixing among inner and outer orbitals of an atom such ascarbon. In carbon, hybridized orbitals can be sp³ hybrids, sp² hybrids,and sp hybrids. Without being bound by theory or a particular mode ofaction, it is believed that organic materials with a high degree of spor sp² hybridization are preferable for forming conductive carboncoatings on active materials. Compounds, according to embodiments of theinvention, contain conjugated cores in which many of the carbon atomsare sp or sp² hybridized. Compounds, according to embodiments of theinvention, may be known for their intrinsic conductivity.

Conductive carbon coatings of the prior art, such as graphitic coatings,are formed from non-conductive carbon molecules with non-hybridized orsp³ hybridized orbital electrons. Such materials are typically heated tohigh temperatures to decompose and graphitize them, often forming carboncoatings with sp² hybridized orbitals. In such coatings, it is knownthat the efficiency of the graphitization increases with temperature andthat high temperature heat treatment gives the best performing coatings.

In contrast, compounds of certain embodiments do not require hightemperature heat treatment due at least in part to their intrinsicconductivity. Compounds of the embodiments of the present invention donot require graphitization to provide a conductive carbon coating.Further, decomposition of compounds of embodiments of the invention maybe undesirable as it would likely reduce or destroy the intrinsicconductivity of the compounds.

According to embodiments of the invention, compounds for coating activematerials contain carbon atoms that are sp or sp² hybridized.Preferably, at least 35% of the carbon atoms in the compound are sp orsp² hybridized. Preferably, at least 40% of the carbon atoms in thecompound are sp or sp² hybridized. Preferably, at least 45% of thecarbon atoms in the compound are sp or sp² hybridized. Preferably, atleast 50% of the carbon atoms in the compound are sp or sp² hybridized.Preferably, at least 55% of the carbon atoms in the compound are sp orsp² hybridized. Preferably, at least 60% of the carbon atoms in thecompound are sp or sp² hybridized. Preferably, at least 65% of thecarbon atoms in the compound are sp or sp² hybridized. Preferably, atleast 70% of the carbon atoms in the compound are sp or sp² hybridized.Preferably, at least 75% of the carbon atoms in the compound are sp orsp² hybridized. Preferably, at least 80% of the carbon atoms in thecompound are sp or sp² hybridized. Preferably, at least 85% of thecarbon atoms in the compound are sp or sp² hybridized. Preferably, atleast 90% of the carbon atoms in the compound are sp or sp² hybridized.Preferably, at least 95% of the carbon atoms in the compound are sp orsp² hybridized. Preferably, 100% of the carbon atoms in the compound aresp or sp² hybridized.

According to embodiments of the invention, compounds for coating activematerials contain conjugated cores in which many of the carbon atoms aresp or sp² hybridized. Preferably, the compounds contain conjugated coresin which at least 35% of the carbon atoms are sp or sp² hybridized.Preferably, the compounds contain conjugated cores in which at least 40%of the carbon atoms are sp or sp² hybridized. Preferably, the compoundscontain conjugated cores in which at least 45% of the carbon atoms aresp or sp² hybridized. Preferably, the compounds contain conjugated coresin which at least 50% of the carbon atoms are sp or sp² hybridized.Preferably, the compounds contain conjugated cores in which at least 55%of the carbon atoms are sp or sp² hybridized. Preferably, the compoundscontain conjugated cores in which at least 60% of the carbon atoms aresp or sp² hybridized. Preferably, the compounds contain conjugated coresin which at least 65% of the carbon atoms are sp or sp² hybridized.Preferably, the compounds contain conjugated cores in which at least 70%of the carbon atoms are sp or sp² hybridized. Preferably, the compoundscontain conjugated cores in which at least 75% of the carbon atoms aresp or sp² hybridized. Preferably, the compounds contain conjugated coresin which at least 80% of the carbon atoms are sp or sp² hybridized.Preferably, the compounds contain conjugated cores in which at least 85%of the carbon atoms are sp or sp² hybridized. Preferably, the compoundscontain conjugated cores in which at least 90% of the carbon atoms aresp or sp² hybridized. Preferably, the compounds contain conjugated coresin which at least 95% of the carbon atoms are sp or sp² hybridized.Preferably, the compounds contain conjugated cores in 100% of the carbonatoms are sp or sp² hybridized.

Examples of compounds containing conjugated cores include but are notlimited to: pentacene, anthracene, naphthalene, rubrene, C60, graphene,multi-walled carbon nanotubes (MWCNT), N,N′-dioctyl-3,4,9,10perylenedicarboximide, perylene, pyrene, tetrathiafulvalene,polyaniline, 6,13-bis(triisopropylsilylethynyl)pentacene,4-(heptadecafluorooctyl) aniline, poly(3-hexylthiophene-2,5-diyl),7,7,8,8-tetracyanoquinodimethane, 11-phenoxylundecanoic acid,triphenylene, poly(2,6-naphthalenevinylene), octofluoronapthalene,oligothiophenes, hexabenzocoronene, phthalocyanine, p-quinquephenyl 8,and tetra-N-phenylbenzidine. More than one compound can be combined in asingle coating to generate additive or enhanced performance.

Examples of carbon source coating materials according to certainembodiments of the invention include but are not limited to: PVDF,tris[4-(5-dicyanomethylidenemethyl-2-thienyl)phenyl]amine, triphenylene,tetrathiafulvalene, rubrene, pyrene, polyaniline (emeraldine base),poly(3-hexylthiophene-2,5-diyl), PNV, perylene-3,4,9,10-tetracarboxylicdianhydride, perylene, pentacene/MWCNT, pentacene/anthracene (4:1),pentacene/anthracene (1:4), pentacene-N-sulfinyl-tert-butylcarbamate,pentacene, naphthalene, N,N′-dioctyl-3,4,9,10-perylenedicarboximide,dithieno[3,2-b:2?,3?-d]thiophene, dilithium phthalocyanine,dibenzotetrathiafuIvalene, dibenz[a,h]anthracene, coronene, copper(II)phthalocyanine, C60, bis(ethylenedithio)tetrathiafulvalene,benz[b]anthracene, anthracene, 29H,31H-phthalocyanine,11-phenoxyundecanoic acid, 7,7,8,8-tetracyanoquinodimethane,6,13-bis(triisopropylsilylethynyl)pentacene,5,10,15,20-tetrakis(pentafluorophenyl)porphyrin,4-(heptadecafluorooctyl)aniline, 2,2′:5′,2″:5″,2′″-quaterthiophene,1,8-naphthalic anhydride, 1,6-diphenyl-1,3,5-hexatriene,1,4,5,8-naphthalenetetracarboxylic dianhydridem,1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzoimidazole, and combinationsthereof.

According to certain embodiments, electrodes for use in electrochemicalcells are formed from an active material, a binder material, and aconductive material. The active material is typically in particulateform, but it may take other forms. Prior to forming the electrode,active materials are coated using compounds according to embodiments ofthe invention. In certain embodiments, the compound “wets” the particlesof the active material. The compound can wet the particles due to beingin solution or due to melting. According to certain embodiments,preferred compounds for coating active material particles would both wetthe particles and form a conductive coating at a temperature below about500 degrees C. According to certain embodiments, preferred carbonprecursors for coating carbon-fluoride particles would both wet theparticles and form a conductive coating at a temperature below about 600degrees C. to about 700 degrees C. Preferably, the compounds produce asubstantially conductive carbon coating at temperatures below the rangeof decomposition temperatures for the active materials.

According to certain embodiments of the invention, the compound is mixedwith a solvent. In these embodiments, solvents are paired with compoundsbased on solubility, wettability, viscosity, flashpoint, volatility, andother properties. The compound and the solvent are mixed using any meansof mixing, including ball milling. In certain embodiments, activematerial and polymer are ball-milled with acetone as a solvent. Examplesof appropriate solvents include acetone, NMP, methanol, hexane,acetonitrile, THF, DMSO, pyridine, benzene, water, ethanol, isopropanol,and combinations thereof. In certain embodiments, the solvent improvesthe wetting of the compound onto active material particles to produce amore uniform and complete coating prior to the heating step. In otherembodiments, the solvent aids the processing of compound particles andactive material particles to improve mixing and/or control particle sizeprior to the heating step. Such improvements in the uniformity andcompleteness of the coating prior to heating provide more uniform andcomplete carbon coatings on the active material after heating.

According to certain embodiments, the active material, compound, andsolvent are mixed using a method such as ball milling. Preferably, theactive material, coating compound, and solvent are mixed using a methodthat produces a substantially uniform and complete coating of thecoating compound on the active material. In some embodiments, the activematerial, compound, and solvent are agitated to produce a substantiallyuniform and complete coating of the compound on the active material. Insome embodiments, the active material and the coating compound are mixedwithout a solvent.

According to certain embodiments, the mixture of the active material,compound, and solvent forms a slurry. In certain embodiments, the slurryis heated to produce a conductive carbon coating on the active material.In certain embodiments, it is preferable for the heating to occur underinert atmosphere.

According to certain embodiments, the heating conditions are chosen toproduce a thin layer of conducting carbon on the active material whilelimiting degradation of the active electrode material. In someembodiments, the heating occurs at a range of temperatures from about300 degrees C. to about 700 degrees C., or preferably from about 400degrees C. to about 600 degrees C. In some embodiments, the heatingoccurs at less than about 500 degrees C. Preferably, the heating occursat less than about 450 degrees C. Preferably, the heating occurs at lessthan about 400 degrees C. Preferably, the heating occurs at less thanabout 350 degrees C. Preferably, the heating occurs at less than about300 degrees C. Preferably, the heating occurs at less than about 250degrees C. Preferably, the heating occurs at less than about 200 degreesC. Preferably, the heating occurs at less than about 150 degrees C.Preferably, the heating occurs at less than about 100 degrees C.

In certain embodiments, it is preferable to tailor the annealing suchthat the sp or sp² hybridized atoms are not decomposed and that thedelocalized electrons of the conjugated cores are substantiallymaintained. However, it is also preferable to provide the system withsufficient energy (e.g., thermal and/or mechanical energy) to yielddesirable coverage on the particles of active material. In certainembodiments, lower annealing temperatures increase battery capacity butreduce voltage performance. In certain embodiments, a reaction occursbetween the coating precursor and the active materials such that thesystem undergoes a color change, which may be evidence of bondingbetween the coating compounds and the active materials.

In some embodiments, the heating occurs for less than about 6 hours.Preferably, the heating occurs for less than about 5 hours. Preferably,the heating occurs for less than about 4 hours. Preferably, the heatingoccurs for less than about 3 hours. Preferably, the heating occurs forless than about 2 hours. Preferably, the heating occurs for less thanabout 1 hour.

According to certain embodiments, the coated active materials arefurther mixed with a binder material and a conductive material. In suchembodiments the mixing can be done by suitable methods, such as ballmilling, to form an electrode-forming material. The electrode-formingmaterial is typically composed primarily of coated active material,preferably in the range of from about 85% to about 97% of activematerial. The remainder of the electrode-forming material is composed ofthe binder material and the conductive material. The binder material istypically present at about 2.5% to about 11%. In certain embodiments,the conductive material is present in a range of from about 0.5% toabout 7.5%.

According to certain embodiments, metal fluoride active materials arecoated using the methods disclosed herein. Coated metal fluoride activematerials may be prepared with or without solvents. Certain of theembodiments exemplified herein were prepared without solvents. Further,coated metal fluoride active materials maybe combined into mixture orcomposites with ionic conductors to improve ionic conduction. Forexample, MoO₃ maybe be used to improve ionic conduction with coated CuF₂active materials. Further, the metal fluoride active materials may beformed into cathode materials using conductive matrix materialsaccording to methods disclosed in copending U.S. Patent Application Ser.No. 61/786,602, Filed Mar. 15, 2013, which application is incorporatedby reference herein in its entirety. Alternately, the conductive matrixmay be formed by combining CuF₂ and a matrix material and then applyingthe conductive coating. Indeed, the components may be combined andapplied in any order. These metal fluorides composites may also benefitfrom the use of an adjunct ionic conductor.

For example, the matrix material LiFePO₄ combined with a coated CuF₂active material demonstrates significant improvement in rate performanceand also demonstrates a low voltage drop when comparing low dischargerates and high discharge rates. These performance benefits are notlimited to CuF₂ and are applicable to other metal fluorides as well.

Unexpectedly, as compared to our work with carbon fluoride activematerials, certain coating precursors did not perform well withconductive matrix materials for use with metal fluoride materials. Forexample, certain conductive matrix materials for use with metal fluorideactive materials coated with dilithium phthalocyanine, perylene, or PVDFdisplayed inferior performance as compared to uncoated conductive matrixmaterials for use with metal fluoride active materials.

As described in the examples below, certain embodiments produce coatedelectrodes that deliver higher power, increased operating voltage,higher capacity at a high discharge rate, and reduced heat buildup whencompared with uncoated electrodes. Without being bound by a particularprinciple, hypothesis, or method of action, coatings of certainembodiments of the invention provide a low resistance pathway forelectron and lithium ion transport, which significantly lowers theelectrode resistance. One consequence of this is an electrochemical cellwith higher power and lower underpotential. As a result, higher capacitycan be obtained when electrochemical cells are run at comparatively highrate.

As illustrated in certain examples herein, the coatings of certainembodiments of the invention address some of the challenges of batteriesby enabling higher power, increasing operating voltage, increasingcapacity at a high discharge rate, reducing heat generation, andincreasing heat dissipation. For example, in high-drain applicationscertain embodiments improve the energy capacity of batteries such that ahigher voltage may be achieved at a high current when compared to priorbatteries. Certain embodiments extend the useful life of batteries undermoderate to high drain conditions. Unexpectedly, the coatings of certainembodiments of the present invention address these challenges at lowconcentrations. Coated cathode materials according to certainembodiments of the invention demonstrated improved voltage and power atlate depths of discharge.

Coated cathode materials according to certain embodiments of theinvention were included in electrochemical cells according to theexamples set forth below. In some situations, the electrolyte solutionin the electrochemical cell included additives according to usingmaterials and methods disclosed in copending U.S. patent applicationSer. No. 13/612,798 filed Sep. 12, 2012 and titled “ElectrolyteMaterials for Batteries and Methods of Use,” which application isincorporated by reference herein in its entirety. The combination of thecoated cathode materials of certain embodiments of the invention andsuch electrolyte solutions including additives demonstrated improvedperformance. In many cases, the performance improvements weresubstantially greater than the performance improvements realized byeither the coating or the additive on its own.

The following examples describe specific aspects of some embodiments ofthe invention to illustrate and provide a description for those ofordinary skill in the art. The examples should not be construed aslimiting the invention, as the examples merely provide specificmethodology useful in understanding and practicing some embodiments ofthe invention.

EXAMPLES Example 1 Fabrication of Conductively Coated Electrodes fromCarbon Precursor Materials

Materials and Synthetic Methods.

Carbon-fluoride active material was milled with carbon precursors atmedium energy, followed by post annealing. Carbon precursors includedKJ600 (carbon black), PEG, PVDF, and sucrose. The carbon precursorloading was 5 wt %. The annealing conditions were 450 and 600 degrees C.for 2 and 6 hours.

Example 2 Fabrication of Conductively Coated Electrodes with and withoutAdditive Materials

Methods were the same as in Example 1, with the following changes:

Poly(vinylidene fluoride) was used as a carbon precursor; the carbonprecursor loading had three conditions (1, 3, 5 wt %); the annealingconditions were 450 and 500 degrees C. at 3, 6 and 12 hours.

Example 3 Fabrication of Conductively Coated Electrodes from ConjugatedCore Compounds

Materials and Synthetic Methods.

All reactions were prepared in a high purity argon filled glove box(M-Braun, O₂ and humidity contents <0.1 ppm). Unless otherwisespecified, materials were obtained from commercial sources (e.g.,Sigma-Aldrich, Advanced Research Chemicals Inc., and Alfa Aesar) andused without further purification.

Carbon Coating.

CFx, LMO and LMNO particles were coated with conductive carbon materialsthrough a milling process. Milling vessels were loaded with the basecathode material, conductive carbon coating precursor materials, andsolvents. The conductive carbon coating precursor materials are loadedin a range of 0-5 wt %. The vessels were sealed and their contents thenmilled. After milling, solvents were evaporated at about 60 degrees C.and, in certain embodiments, samples were annealed under flowing N₂.

Electrode Formulation.

In the case of coated CFx particles, electrodes were prepared with aformulation composition of 85% active materials, 11% binder materials,and 4% conductive additive according to the following formulationmethod: About 200 milligrams PVDF (Sigma Aldrich) was dissolved in 10milliliters NMP (Sigma Aldrich) overnight. About 72.7 milligrams ofconductive additive was added to the solution and allowed to stir forseveral hours. About 154 milligrams of coated CFx solid was added to 1milliliters of this solution and stirred overnight. Films were cast bydropping about 100 microliters of slurry onto stainless steel currentcollectors and drying at 150 degrees C. for about 1 hour. Dried filmswere allowed to cool, and were then pressed at a pressure of 1 ton/cm².Electrodes were further dried at 150 degrees C. under vacuum for 12hours before being brought into a glove box for battery assembly.

Electrode Formulation.

In the case of coated LMO, LMNO, and OLO particles, electrodes wereprepared with a formulation composition of 85% active materials, 7.5%binder materials, and 7.5% conductive additive according to thefollowing formulation method: About 198 milligrams PVDF (Sigma Aldrich)and about 198 milligrams of Super P Li (Timcal) were dissolved in 15milliliters NMP (Sigma Aldrich) overnight. About 150 milligrams ofcoated LMO, LMNO, or OLO solid was added to 1 milliliters of thissolution and stirred overnight. Films were cast by dropping about 66microliters of slurry onto stainless steel current collectors and dryingat 150 degrees C. for about 1 hour. Dried films were allowed to cool andwere then pressed at a pressure of 1 ton/cm². Electrodes were furtherdried at 150 degrees C. under vacuum for 12 hours before being broughtinto a glove box for battery assembly.

Example 4 Formation of Electrochemical Cells Containing CoatedElectrodes

All batteries were assembled in a high purity argon filled glove box(M-Braun, O₂ and humidity contents <0.1 ppm), unless otherwisespecified.

Primary CFx cells were made using lithium as an anode, Celaguard 2400 asa separator, and 180 microliters of 1M LiBF₄ in 1:1 PC:DME as anelectrolyte.

Secondary LMO and LMNO half cells were made using lithium as an anode,Celaguard 2400 as a separator and 90 microliters of 1M LiPF₆ in 1:2EC:EMC (Novalyte) as an electrolyte.

Example 5 Testing of Electrochemical Cells Containing Coated Electrodes

Electrochemical cells formed according to Examples 1 and 2 were testedusing a variety of test methods. When compared to electrochemical cellswithout coated electrodes, certain electrochemical cells exhibitedincreases in performance.

For example, as depicted in FIG. 1, coated electrodes resulted in abouta 100-150 mV increase in open circuit voltage in a CFx/SVO hybrid cellbelow 60% depth of discharge (DoD). As depicted in FIG. 1, coatedelectrodes resulted in about a 50-150 mV increase in operating voltagefrom 20-60% depth of discharge (DoD) in a CFx/SVO hybrid cell. Asdepicted in FIG. 2, coated electrodes resulted in about a 0.2 mW/cm²increase in pulse power at 2 mA/cm² pulse current in a CFx/SVO hybridcell at and below 60% DoD. As depicted in FIG. 3, coated electrodesusing as low as half of the conductive additive in the standardelectrode formulation resulted in about a 0.1 mW/cm² increase in pulsepower at 2 mA/cm² pulse current in a CFx/SVO hybrid cell at 60% DoDcompared to the standard formulation with uncoated CFx. As depicted inFIG. 4, coated electrodes behave synergistically with some electrolyteadditives resulting in 0.1-0.2 mW/cm² increase in pulse power at 2mA/cm² pulse current in a CFx/SVO hybrid cell at 60-80% DoD compared tothe coated electrode without electrolyte additive. As depicted in FIG.5, coated electrodes resulted in about a 5 mW/cm² increase in pulsepower at 25 mA/cm² pulse current in a CFx/SVO hybrid cell at 60% DoD. Asdepicted in FIG. 6, coated electrodes prepared using both fluorinated(PVDF) and non-fluorinated (PEG) carbon precursors resulted in about a0.2-0.3 mW/cm² increase in pulse power at 2 mA/cm² pulse current in aCFx/SVO hybrid cell at and below 50% DoD.

Example 6 Testing Protocol for Primary Electrochemical Cells ContainingCoated Electrodes

Electrodes and cells designed as primary cells were electrochemicallycharacterized at 30 degrees C. using a constant current dischargeprotocol at 0.1 C and 1 C.

Example 7 Testing Protocol for Secondary Electrochemical CellsContaining Coated Electrodes

Electrodes and cells designed as secondary were electrochemicallycharacterized at room temperature (˜23° C.) using the followingprotocol: (1) cells were conditioned in a cycle where charging anddischarging took place at a C-rate of C/20, including a constantcurrent, constant voltage discharge until the current reached C/100; (2)cells were tested for charge capacity retention by stepping throughvarious C-rates (2 C, 1 C, 0.5 C, 0.1 C) with 3 hour open current holdperiods in between each C-rate. For LMO active materials, the chargingvoltage was 4.5V. For LMNO active materials, the charging voltage was4.95V. The cells are discharged by stepping through various C-rates (2C, 1 C, 0.5 C, 0.1 C) with 3 hour open current hold periods in betweeneach C-rate; (3) cells were cycled to produced an over-lithiated phaseby cycling at a charge and discharge C-rate of C/10, including a 3 houropen current hold period; and (4) cells were tested again as in step(2).

Example 8 Testing of Primary Electrochemical Cells Containing CoatedElectrodes

Primary cells assembled according to Examples 3 and 4 with a CFx cathodewere tested according to Example 6. The cathodes in the 0.1 C dischargetest consisted of: (1) uncoated CFx active material; (2) CFx activematerial coated according to graphitization methods with a carboncoating deposited using a PVDF precursor material; and (3) CFx activematerial coated with pentacene. FIG. 7 illustrates an improvement in theoperating voltage in the pentacene-coated sample.

Example 9 Testing of Primary Electrochemical Cells Containing CoatedElectrodes

Primary cells assembled according to Examples 3 and 4 with a CFx cathodewere tested according to Example 6. The cathodes in the 1 C dischargetest consisted of: (1) uncoated CFx active material; (2) CFx activematerial coated with MWCNT; (3) CFx active material coated withpentacene; and (4) CFx active material coated with a mixture of MWCNTand pentacene. FIG. 8 illustrates an improvement in the operatingvoltage and the voltage delay in the pentacene-coated and thepentance/MWCNT samples.

Example 10 Testing of Primary Electrochemical Cells Containing CoatedElectrodes

Primary cells assembled according to Examples 3 and 4 with a CFx cathodewere tested according to Example 6. The cathodes in the 1 C dischargetest consisted of: (1) uncoated CFx active material; (2) CFx activematerial coated with 7,7,8,8-tetracyanoquinodimethane; (3) CFx activematerial coated with tetrathiafulvalene; and (4) CFx active materialcoated with a mixture of tetrathiafulvalene and7,7,8,8-tetracyanoquinodimethane. FIG. 9 illustrates an improvement inthe operating voltage and the voltage delay in the mixture oftetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane samples.

Example 11 Testing of Secondary Electrochemical Cells Containing CoatedElectrodes

Secondary cells were assembled according to Examples 3 and 4. Thecathodes in the test consisted of: (1) uncoated LMO active material; (2)uncoated LMNO active material; (3) LMO active material coated withrubrene; and (4) LMNO active material coated with rubrene; (5) LMOactive material coated with N,N′-dioctyl-3,4,9,10 perylenedicarboximide;and (6) LMNO active material coated with N,N′-dioctyl-3,4,9,10perylenedicarboximide. FIGS. 10A (LMO) and 10B (LMNO) illustrate animprovement in the capacity retention at high C rates for the coatedmaterials.

Example 12 Voltage and Power Testing of Electrochemical Cells ContainingCoated Electrodes

Electrodes and cells were electrochemically characterized at 37 degreesC. using the following protocol: 0.01 C background discharge with highcurrent pulsing at predefined depths of discharge for powermeasurements. Pulsing was carried out at 5 mA/cm² for 10 secondsfollowed by 10 seconds of OCV. Pulsing was done in sets of four pulsesand the cell rested at OCV for 10 hours prior to the first pulse andafter the fourth pulse. FIG. 11 illustrates the pulse power improvementof the best carbon coated CF_(x) at 80% depth of discharge.

Table 1 lists coating materials tested and their performance in voltageand rate capability testing as compared to a control. Cells werefabricated using a hybrid cathode (CFx/SVO) material coated with thecarbon source listed in Table 1. Rate capability is expressed as thepercentage of the discharge at C rate as compared to 0.1 C rate.

TABLE 1 Performance of Coating Materials Rate Anneal Voltage CapabilityTemp at 1 C C/0.1 C Carbon Source (degrees C.) (V) (%) Control 0 2.2078.54 PVDF 450 2.27 75.02 Tris[4-(5-dicyanomethylidenemethyl- 450 2.3478.67 2-thienyl)phenyl]amine Triphenylene 250 2.21 62.09Tetrathiafulvalene 250 2.26 76.22 Rubrene 425 2.41 86.37 Pyrene 300 2.2877.64 Polyaniline (emeraldine base) 400 2.33 77.94Poly(3-hexylthiophene-2,5-diyl) 300 2.27 No Data PNV 300 2.25 55.74Perylene-3,4,9,10-tetracarboxylic 400 2.33 77.85 dianhydride Perylene400 2.41 85.81 Pentacene/MWCNT 400 2.30 76.75 Pentacene/Anthracene (4:1)250 2.29 78.88 Pentacene/Anthracene (1:4) 250 2.27 75.86Pentacene-N-sulfinyl-tert- 350 2.31 74.36 butylcarbamate Pentacene 4002.39 81.20 Napthalene 100 2.24 75.42 N,N′-Dioctyl-3,4,9,10- 425 2.40 NoData perylenedicarboximide Dithieno[3,2-b:2?,3?-d]thiophene 0 2.29 NoData Dilithium phthalocyanine 400 2.35 79.18 Dibenzotetrathiafulvalene300 2.27 78.08 Dibenz[a,h]anthracene 350 2.33 80.46 Coronene 450 2.3681.51 Copper(II) phthalocyanine 400 2.30 77.71 C60 350 2.17 51.84Bis(ethylenedithio)tetrathiafulvalene 300 2.29 80.03 Benz[b]anthracene400 2.35 78.46 Anthracene 250 2.27 76.13 29H,31H-Phthalocyanine 350 2.3377.22 11-Phenoxyundecanoic acid 100 2.24 70.087,7,8,8-Tetracyanoquinodimethane 300 2.24 73.52 6,13- 0 2.24 74.72Bis(triisopropylsilylethynyl)pentacene 5,10,15,20- 350 2.29 79.19Tetrakis(pentafluorophenyl)porphyrin 4-(Heptadecafluorooctyl)aniline 1002.24 71.59 2,2′:5′,2″:5″,2′″-Quaterthiophene 250 2.22 75.031,8-Naphthalic anhydride 350 2.24 68.58 1,6-Diphenyl-1,3,5-hexatriene200 2.23 67.38 1,4,5,8-Naphthalenetetracarboxylic 350 2.28 68.75dianhydride 1,3-Dimethyl-2-phenyl-2,3-dihydro- 150 2.30 77.851H-benzoimidazole

Table 2 lists coating materials tested using a hybrid cathode (CFx/SVO)material coated with the carbon source listed in Table 2. Table 2reports the power measured for the cell at 70% depth of discharge and at80% depth of discharge.

TABLE 2 Performance of Coating Materials Anneal Power Power Temp (70%(80% (degrees Capacity, Capacity, Carbon Source C.) mW/cm²) mW/cm²)Control 0 12.08 11.50 PVDF 450 12.15 11.70Tris[4-(5-dicyanomethylidenemethyl- 450 12.07 11.472-thienyl)phenyl]amine Triphenylene 250 No Data No DataTetrathiafulvalene 250 No Data No Data Rubrene 425 No Data No DataPyrene 300 No Data No Data Polyaniline (emeraldine base) 400 No Data NoData Poly(3-hexylthiophene-2,5-diyl) 300 No Data No Data PNV 300 No DataNo Data Perylene-3,4,9,10-tetracarboxylic 400 11.49 10.51 dianhydridePerylene 400 No Data No Data Pentacene/MWCNT 400 No Data No DataPentacene/Anthracene (4:1) 250 No Data No Data Pentacene/Anthracene(1:4) 250 No Data No Data Pentacene-N-sulfinyl-tert- 350 11.72 11.40butylcarbamate Pentacene 400 No Data No Data Napthalene 100 No Data NoData N,N′-Dioctyl-3,4,9,10- 425 No Data No Data perylenedicarboximideDithieno[3,2-b:2?,3?-d]thiophene 0 No Data No Data Dilithiumphthalocyanine 400 10.13  9.88 Dibenzotetrathiafulvalene 300 11.79 11.33Dibenz[a,h]anthracene 350 10.96 10.52 Coronene 450 11.77 10.87Copper(II) phthalocyanine 400 12.18 11.86 C60 350 No Data No DataBis(ethylenedithio)tetrathiafulvalene 300 11.85 11.45 Benz[b]anthracene400 11.95 11.26 Anthracene 250 No Data No Data 29H,31H-Phthalocyanine350 No Data No Data 11-Phenoxyundecanoic acid 100 No Data No Data7,7,8,8-Tetracyanoquinodimethane 300 No Data No Data 6,13- 0 No Data NoData Bis(triisopropylsilylethynyl)pentacene 5,10,15,20- 350 12.03 11.53Tetrakis(pentafluorophenyl)porphyrin 4-(Heptadecafluorooctyl)aniline 100No Data No Data 2,2′:5′,2″:5″,2′″-Quaterthiophene 250 11.89 11.461,8-Naphthalic anhydride 350 12.55 11.92 1,6-Diphenyl-1,3,5-hexatriene200 No Data No Data 1,4,5,8-Naphthalenetetracarboxylic 350 12.50 11.88dianhydride 1,3-Dimethyl-2-phenyl-2,3-dihydro- 150 11.91 11.501H-benzoimidazole

Table 3 lists coating materials tested and their performance in voltageand rate capability testing as compared to a control. Cells werefabricated using a pure CFx cathode material coated with the carbonsource listed in Table 3. Rate capability is expressed as the percentageof the discharge at C rate as compared to 0.1 C rate.

TABLE 3 Performance of Coating Materials Rate Anneal Voltage CapabilityTemp at 1 C C/0.1 C Carbon Source (degrees C.) (V) (%) Control 0 2.1660.50 PVDF 450 2.23 64.15 Tris[4-(5-dicyanomethylidenemethyl- 450 NoData No Data 2-thienyl)phenyl]amine Triphenylene 250 No Data No DataTetrathiafulvalene 250 2.16 62.55 Rubrene 425 2.25 74.25 Pyrene 300 2.1773.25 Polyaniline (emeraldine base) 400 2.24 66.84Poly(3-hexylthiophene-2,5-diyl) 300 No Data No Data PNV 300 No Data NoData Perylene-3,4,9,10-tetracarboxylic 400 No Data No Data dianhydridePerylene 400 2.24 65.42 Pentacene/MWCNT 400 2.23 79.15Pentacene/Anthracene (4:1) 250 No Data No Data Pentacene/Anthracene(1:4) 250 No Data No Data Pentacene-N-sulfinyl-tert- 350 No Data No Databutylcarbamate Pentacene 400 2.26 68.46 Napthalene 100 2.16 76.51N,N′-Dioctyl-3,4,9,10- 425 No Data No Data perylenedicarboximideDithieno[3,2-b:2?,3?-d]thiophene 0 No Data No Data Dilithiumphthalocyanine 400 No Data No Data Dibenzotetrathiafulvalene 300 No DataNo Data Dibenz[a,h]anthracene 350 No Data No Data Coronene 450 No DataNo Data Copper(II) phthalocyanine 400 No Data No Data C60 350 2.22 73.49Bis(ethylenedithio)tetrathiafulvalene 300 No Data No DataBenz[b]anthracene 400 No Data No Data Anthracene 250 2.22 89.1329H,31H-Phthalocyanine 350 2.22 68.41 11-Phenoxyundecanoic acid 100 2.1782.40 7,7,8,8-Tetracyanoquinodimethane 300 2.16 60.39 6,13- 0 No Data NoData Bis(triisopropylsilylethynyl)pentacene 5,10,15,20- 350 No Data NoData Tetrakis(pentafluorophenyl)porphyrin4-(Heptadecafluorooctyl)aniline 100 2.20 80.632,2′:5′,2″:5″,2′″-Quaterthiophene 250 No Data No Data 1,8-Naphthalicanhydride 350 No Data No Data 1,6-Diphenyl-1,3,5-hexatriene 200 2.1884.30 1,4,5,8-Naphthalenetetracarboxylic 350 No Data No Data dianhydride1,3-Dimethyl-2-phenyl-2,3-dihydro- 150 No Data No Data 1H-benzoimidazole

Example 13 Fabrication of Conductively Coated Metal Fluoride Electrodes

Materials and Synthetic Methods.

All reactions were prepared in a high purity argon filled glove box(M-Braun, O₂ and humidity contents <0.1 ppm). Unless otherwisespecified, materials were obtained from commercial sources(Sigma-Aldrich, Advanced Research Chemicals Inc, Alfa Aesar, Strem, etc)without further purification.

Carbon Coating.

CuF₂ was coated through a two-step milling process. Milling vessels werefirst loaded with CuF₂ and MoO₃ (15 wt %), sealed, and then milled. Themilling vessels were opened under argon gas and carbon coating precursormaterials (5 wt %) were added. The milling vessels were sealed andmilled at low energy. After milling, samples were annealed under flowingN₂.

Electrode Formulation.

Electrodes were prepared with a formulation composition of 80% activematerials, 15% binder, and 5% conductive additive according to thefollowing formulation method: about 133 mg PVDF (Sigma Aldrich) andabout 44 mg Super P Li (Timcal) was dissolved in 10 mL NMP (SigmaAldrich) overnight. 70 mg of coated CuF₂ powder was added to 1 mL ofthis solution and stirred overnight. Films were cast by dropping about70 L of slurry onto stainless steel current collectors and drying at 150degrees C. for about 1 hour. Dried films were allowed to cool, and werethen pressed at 1 ton/cm². Electrodes were further dried at 150 degreesC. under vacuum for 12 hours before being brought into a glove box forbattery assembly.

Example 14 Electrochemical Characterization of Conductively Coated MetalFluoride Electrodes

All batteries were assembled in a high purity argon filled glove box(M-Braun, O₂ and humidity contents <0.1 ppm), unless otherwisespecified. Cells were made using lithium as an anode, Celgard 2400separator, and 90 L of 1M LiPF₆ in 1:2 EC:EMC electrolyte. Electrodesand cells were electrochemically characterized at 30 degrees C. usingthe following protocol: constant current discharge at 1 C, 0.5 C, 0.2 C,0.1 C, 0.05 C, and 0.02 C rate to 2.0 V cutoff.

As depicted in FIG. 12, CuF₂ coated with anthracene and naphthalicanhydride showed an improvement over uncoated CuF₂. Anthracene coatedCuF₂ (annealed at about 250 degrees C.) demonstrated about 94% rateretention and naphthalic anhydride coated CuF₂ (annealed at about 300degrees C.) demonstrated about 92% rate retention at first cycle whencomparing 0.1 C rate and 0.02 C rate discharge. Other coatings on CuF₂,such as PVDF annealed at about 450 degrees C., demonstrated inferiorrate capability as compared to uncoated CuF₂. As depicted in FIG. 13, ananthracene coated CuF₂/MoO₃ composite material demonstrates improvementin rate performance as compared to an uncoated CuF₂/MoO₃ compositematerial for rates from 0.02 C to 1 C. In particular, the anthracenecoated material showed significant improvement in rate performance athigher discharge rates as compared to the uncoated control material. Asdepicted in FIG. 14, there is a low voltage drop from 0.1 C to 1 C ratefor an anthracene coated material. Further, the coated material shows anenergy density of 285 mAh/g at 1 C rate. FIG. 15 depicts further energydensity improvements in a CuF₂/MoO₃ composite material coated accordingto embodiments of the invention. The energy density at 1 C rate isgreater than about 375 mAh/g and at lower rates the energy densityapproaches or exceeds 400 mAh/g. Further, FIG. 15 demonstrates a lowvoltage drop from 0.01 C to 1 C rate due to the conductive coating

Various materials disclosed herein demonstrated improved performance ascompared to control. In certain testing, naphthalic anhydridedemonstrated a 3% capacity improvement, power performance improvement,and improved power stability over control. In certain testing, perylenedemonstrated a 9% voltage improvement over control. In certain testing,rubrene demonstrated superior capacity at high voltage as compared tocontrol.

While the invention has been described with reference to the specificembodiments thereof, it should be understood by those skilled in the artthat various changes may be made and equivalents may be substitutedwithout departing from the true spirit and scope of the invention asdefined by the appended claims. In addition, many modifications may bemade to adapt a particular situation, material, composition of matter,method, or process to the objective, spirit and scope of the invention.All such modifications are intended to be within the scope of the claimsappended hereto. In particular, while the methods disclosed herein havebeen described with reference to particular operations performed in aparticular order, it will be understood that these operations may becombined, sub-divided, or re-ordered to form an equivalent methodwithout departing from the teachings of the invention. Accordingly,unless specifically indicated herein, the order and grouping of theoperations are not limitations of the invention.

The invention claimed is:
 1. A method of making an electrode for anelectrochemical cell, comprising: combining a coating composition and anactive electrode material to form a mixture, wherein the coatingcomposition comprises a coating precursor in which at least 35% ofcarbon atoms in the coating precursor are sp or sp² hybridized; heatingthe mixture for a time and at a temperature that limits degradation ofthe active electrode material; mixing the coated active electrodematerial with a binder material and a conductive additive to form anelectrode-forming mixture; and heating the electrode-forming mixture toform the electrode.
 2. The method of claim 1 wherein the activeelectrode material comprises an oxide compound, fluoride compound, aphosphate compound, or a silicate compound.
 3. The method of claim 1wherein the mixture is heated for a time that limits degradation of theactive electrode material.
 4. The method of claim 1 wherein the firstheating step forms a covalently attached coating on the active electrodematerial.
 5. The method of claim 1 wherein at least 90% of carbon atomsin the coating precursor are sp or sp² hybridized.
 6. The method ofclaim 1 wherein 100% of carbon atoms in the coating precursor are sp orsp² hybridized.
 7. The method of claim 1 wherein the coating precursorcomprises a core in which 90% of carbon atoms in the core are sp or sp²hybridized.
 8. The method of claim 1 wherein the coating precursorcomprises a core in which 100% of carbon atoms in the core are sp or sp²hybridized.
 9. The method of claim 3 wherein the mixture is heated for atime in a range of from about 0.5 hours to about 6 hours.
 10. The methodof claim 1 wherein the coating precursor comprises naphthalene.
 11. Themethod of claim 1 wherein the coating precursor comprises pentacene. 12.The method of claim 1 wherein the coating precursor comprisesanthracene.
 13. The method of claim 2 wherein the active electrodematerial comprises an oxide compound and the oxide compound comprises ametal oxide compound.
 14. The method of claim 13 wherein the oxidecompound comprises a lithium-manganese-nickel-oxygen compound.
 15. Themethod of claim 13 wherein the oxide compound comprises alithium-manganese-oxygen compound.
 16. The method of claim 13 whereinthe oxide compound comprises a lithium-rich layered oxide compound. 17.The method of claim 2 wherein the active electrode material comprises afluoride compound and the fluoride compound comprises a metal fluoridecompound.
 18. The method of claim 2 wherein the active electrodematerial comprises a phosphate compound and the phosphate compoundcomprises a metal phosphate compound.
 19. The method of claim 18 whereinthe phosphate compound comprises a lithium-iron-phosphate compound. 20.The method of claim 2 wherein the active electrode material comprises asilicate compound and the silicate compound comprises a metal silicatecompound.